Resist pattern thickening material and process for forming resist pattern, and semiconductor device and process for producing the same

ABSTRACT

The object of the present invention is to provide a process for forming a resist pattern that is capable to utilize excimer laser beam, the thickening level of the resist pattern is controllable uniformly, constantly and precisely, without being affected substantially by environmental changes such as temperatures and humidity, and storage period, and space pattern of resist may be formed with a fineness exceeding exposure limits or resolution limits of available irradiation sources. The process for producing a semiconductor device is characterized in that forming a resist pattern on a surface of workpiece, coating a resist pattern thickening material on the resist pattern, thickening the resist pattern to form a thickened resist pattern, and patterning the surface of workpiece by etching using the thickened resist pattern as a mask, wherein the resist pattern thickening material comprises a resin, and exhibits a pH value of above 7 and not over 14 at coating or after coating on the resist pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefits of the priorityfrom the prior Japanese Patent Application No. 2004-291910, filed onOct. 4, 2004, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a resist pattern thickening material,which is applied over a resist pattern and is capable of thickening theresist pattern, and which may form a fine space pattern that exceedsexposure limit of laser beam or light of available exposure devices. Thepresent invention also relates to a process for forming a resistpattern, a semiconductor device, and a process for producing thesemiconductor device that utilize the resist pattern thickening materialrespectively.

2. Description of the Related Art

Currently, semiconductor integrated circuits have been progressed intofiner and more precise integration, and LSIs and VLSIs are utilizedcommercially. Along with these trends, the wiring patterns extend toregions of 200 nm or less, in particular cases extend to regions as lowas 100 nm or less. Lithographic technologies are extremely important forforming fine wiring patterns, in which a substrate is coated by a resistfilm, then is selectively exposed, and then is developed to form aresist pattern. Typically, dry etching is carried out by using resistpatterns as a mask, and desired patterns are produced by removing theresist patterns.

In order to improve such wiring patterns utilizing the lithographictechnologies, it is necessary to make the light or beam from exposuredevices shorter wavelength and also to develop resist materials that areof high resolution and are suitable to the irradiation source. However,in order to make light or beam from an exposure device shorterwavelength, time consuming and expensive researches are required.Further, the developments of new resist materials are not easy that areutilized for exposing light or beam with shorter wavelength.

Accordingly, various technologies have been proposed to form fine resistpatterns by means of resist pattern thickening materials in order toform finer patterns.

For example, Japanese Patent Application Laid-Open (JP-A) No. 10-73927disclose a proposal that forms fine space patterns using KrF (kryptonfluoride) excimer laser beam of wavelength 248 nm which is deepultraviolet light as the exposure light of a resist. In this proposal,resist patterns are formed by exposing a resist of positive resist ornegative resist using KrF excimer laser beam of wavelength 248 nm as theexposure light. Thereafter, by means of a water-soluble resincomposition, a coated film is provided so as to cover the resistpattern. The coated film and the resist pattern are made to interact atthe interface thereof using the residual acid within the material of theresist pattern, and the resist pattern is thickened (hereinafter, thethickening of the resist pattern being sometimes referred to as“swelling”). In this way, the distance between the resist patterns isshortened, and a fine pattern is formed that has the same form as thespace pattern.

This proposal makes use of residual acid in the resist pattern tothicken the resist pattern through acid-based reactions, thereforesuffers from significant alternation of thickened level due to theenvironmental conditions such as temperature, alkaline contamination,and other conditions, resulting in hardly controllable thickened level.

JP-A No. 2001-33984 proposes coating basic organic films onnegative-type resist patterns that contain acid components, then heatingand irradiating. In this proposal, there exist some disadvantages thatthe resist patterns are limited to negative-type; the process iscomplicated such that optical irradiation is necessary after the basicorganic film is coated; the basic organic film is utilized for no morethan making soluble the hydroxy oxide group in phenol compounds in thenegative-type resist patterns.

JP-A No. 2002-6512 proposes coating the surface of positive-type resistpatterns containing acid components by a first overlay containing acidcomponents and then a second overlay, followed by heating and opticalirradiation, thereby making slim the resist pattern without changing thefilm thickness of the positive-type resist pattern. However, thisproposal suffers from the complicated process in that it requires twooverlays on the resist pattern.

From the view point to form fine wiring patterns, laser beam having awave length shorter than 248 nm of KrF excimer laser is desirable suchas ArF (argon fluoride) excimer laser having a wave length of 193 nm. Onthe other hand, pattern formation by means of X-ray, electron beam orthe like having a wave length shorter than 193 nm of ArF excimer laserinevitably leads to higher cost and lower productivity, therefore,employment of the ArF excimer laser is desirable.

In the case of fine space pattern formed by resist patterns such as theArF resist, about a few tens nano meters (nm) is sufficient level tothicken or swell. Thickening over desired level may possibly bring abouta desirable result; in some cases, no more than mere improvement as toedge roughness of resist patterns may bring about a sufficient result.

However, in the prior art, the level of thickening or swelling is hardlycontrollable with respect to resist patters, thus fine patterns arehardly obtainable under delicate controls in general. Further, the priorart typically suffers from significantly unstable thickening or swellinglevel; the levels of thickening or swelling may be different dependingon the irradiating pattern in the prior art; for example, independentrectangular patterns tend to result in larger thickening or swellinglevel in longer direction than that in shorter direction; hole patternstend to result in various thickening or swelling levels depending on thepattern density; and/or the level of thickening or swelling oftendiffers depending on the pattern site on a wafer.

Moreover, conventional resist pattern thickening materials are notsufficient in storage stability, there may arise a problem that thethickening level is different depending on the storage period, whichcause an undesirable problem in order to apply to processes forproducing semiconductors.

Accordingly, an object of the present invention is to provide a resistpattern thickening material that may exhibit superior storage stabilityand may thicken a resist pattern uniformly, constantly and precisely,without being affected substantially by environmental changes such astemperatures and humidity, and storage period.

Another object of the present invention is to provide a process forforming a resist pattern that is capable to utilize excimer laser beam,the thickening level of the resist pattern is controllable uniformly,constantly and precisely, without being affected substantially byenvironmental changes such as temperatures and humidity, and storageperiod, and space pattern of resist may be formed with a finenessexceeding exposure limits or resolution limits of available irradiationsources.

Another object of the present invention is to provide a semiconductordevice having a fine wiring pattern that is formed by means of a finespace pattern of resist that is formed by means of the resist patternthickening material according to the present invention, and a processfor producing a semiconductor device adapted to effective massproduction of the semiconductor device.

SUMMARY OF THE INVENTION

Inventors of the present invention have investigated vigorously in orderto solve the problems described above, and have found the followingexperiences or discoveries. In the process to thicken resist patterns bycoating a resist pattern thickening material or swelling material on theresist pattern, when the resist pattern is thickened through acid-basedreactions by making use of residual acid in the resist pattern asdisclosed in JP-A No. 10-73927, the thickening level dependssignificantly on environment factors such as temperature and alkalinecontamination thus is hardly controllable in general. On the other hand,when making use of a reaction that does not require an acid to thickenthe resist pattern, formation of fine patterns can be stably realized ina condition that acid-based reactions cannot progress. Further, althoughsome components such as polyvinylacetal resin in the resist patternthickening material may yield a free acid during a prolonged storage, ifthe free acid can be neutralized, the resist pattern thickening materialmay serve as a material that provides superior storage stability andprocess uniformity and consistency without causing change or degrade ofthe desirable properties during the storage.

The present invention is based on such experiences or discoveries; howto solve aforesaid problems is described in attached claims.

The resist pattern thickening material according to the presentinvention is utilized to thicken a resist pattern by coating on theresist pattern, comprises a resin, and have a pH value of above 7 andnot over 14 at coating on the resist pattern or after the coating on theresist pattern.

When the resist pattern thickening material is applied over a resistpattern to be thickened, the portions of the applied resist patternthickening material in a vicinity of the interface with the resistpattern to be thickened infiltrate into the resist pattern and cause aninteraction, i.e., mixing, with the material of the resist pattern to bethickened. Then, because the affinity is high between the resist patternthickening material and the resist pattern to be thickened, a surfacelayer or mixing layer, where the resist pattern thickening material andthe resist pattern are mixed, is efficiently formed on the surface ofthe resist pattern as the inner layer. As a result, the resist patternto be thickened is efficiently thickened by the resist patternthickening material. The resist pattern thickened in this way(hereinafter sometimes referring to as “swelled”) may be thickeneduniformly by the resist pattern thickening material. Thus, the spacepattern of resist formed by the thickened resist pattern may display afiner structure that exceeds an exposure limit or resolution limit byleaser beam. The term “space pattern” is hereby defined as a hole,groove, recess, or any other empty space that is formed by developing aresist.

The resist pattern thickening material according to the presentinvention exhibits a pH value of above 7 and not over 14 at coating onthe resist pattern or after the coating on the resist pattern.Accordingly, the resist pattern thickening material and the resistpattern may be interacted by a reaction in which acid does not intervene(hereinafter, the reaction being sometimes referred to as “non-acidreaction”), that is, the resist pattern thickening material and theresist pattern may be interacted under other than acid-based reactionthat tends to provide unstable factors. Consequently, uniform thickeningeffect may be derived without being affected by species or sizes of theresist pattern, and the resist pattern thickening material of thepresent invention may be suitably utilized for forming a resist pattern,such as a line-space pattern, on a wiring layer of LOGIC LSI wherevarious sizes of resist patterns are utilized.

The process for forming a resist pattern according to the presentinvention is characterized in that the resist pattern thickeningmaterial is coated on the resist pattern and the resist pattern isthickened.

In the process for forming a resist pattern according to the presentinvention, after a resist pattern to be thickened is formed, the resistpattern thickening material of the present invention is applied so as tocover the surface of the resist pattern and the resist pattern isthickened. In the process for forming a resist pattern, when the resistpattern thickening material is applied over a resist pattern, theportions of the applied resist pattern thickening material in a vicinityof the interface with the resist pattern to be thickened infiltrate intothe resist pattern and cause an interaction or mixing with the materialof the resist pattern. Thus, at the surface of the resist pattern, theresist pattern thickening material and the resist pattern undergointeraction, and the resist pattern to be thickened is thickened to forma surface layer or mixing layer. At this stage, the resist patternthickening material according to the present invention exhibits a pHvalue of above 7 and not over 14 (7<pH≦14) at coating on the resistpattern or after the coating on the resist pattern. Accordingly, theresist pattern thickening material and the resist pattern may beinteracted by aforesaid non-acid reaction without the acid-basedreaction that provides unstable factors. Consequently, uniformthickening effect may be derived without being affected by species orsizes of the resist pattern, thus the resist pattern thickening materialaccording to the present invention can be suitably utilized for forminga resist pattern. The resist pattern, which is formed in this way, hasbeen uniformly thickened by the resist pattern thickening material.Thus, the space pattern formed by the resist pattern exceeds an exposurelimit or resolution limit and has a finer structure, and may be appliedto the production of semiconductor devices and the like.

The process for producing a semiconductor device according to thepresent invention is characterized in that it comprises forming a resistpattern on a surface of workpiece, coating the resist pattern thickeningmaterial according to the present invention thereby to thicken theresist pattern and to form a thickened resist pattern, thereafterpatterning the surface of workpiece by an etching process using thethickened resist pattern as a mask.

In the process for producing a semiconductor device according to thepresent invention, formation of a thickened resist pattern is carriedout by forming a resist pattern on a surface of workpiece to be providedwith a wiring pattern for example, then coating the resist patternthickening material on the resist pattern, thereby the resist pattern isthickened to form a thickened resist pattern. Namely, when the resistpattern thickening material according to the present invention is coatedon the resist pattern, the portions of the applied resist patternthickening material in a vicinity of the interface with the resistpattern infiltrate into the resist pattern and cause an interaction ormixing with the material of the resist pattern. Thus, at the surface ofthe resist pattern to be thickened, the resist pattern thickeningmaterial and the resist pattern undergo interaction, and the resistpattern to be thickened is thickened to form a surface layer or mixinglayer. At this stage, the resist pattern thickening material accordingto the present invention exhibits a pH value of above 7 and not over 14(7<pH≦14) at coating on the resist pattern or after the coating on theresist pattern. Accordingly, the resist pattern thickening material andthe resist pattern may be interacted by the non-acid reaction withoutthe acid-based reaction that provides unstable factors. Consequently,uniform thickening effect may be derived without being affected byspecies or sizes of the resist pattern, and the resist patternthickening material according to the present invention is suitablyutilized for forming a resist pattern. The resist pattern, which isformed in this way, has been uniformly thickened by the resist patternthickening material. Thus, the space pattern formed by the resistpattern exceeds an exposure limit or resolution limit and has a finerstructure.

In patterning, etching is carried out by means of the thickened resistpattern formed by the process of thickening a resist pattern; therefore,the surface of workpiece can be patterned finely and precisely withaccurate dimension, thus high-quality and high performance semiconductordevices can be produced efficiently having a wiring pattern with fine,precise, and accurate dimension.

The semiconductor device according to the present invention may beproduced by the process for producing a semiconductor device accordingto the present invention, thereby having fine and accurate patterns ofwiring patterns for example, and being high quality and highperformance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for explaining one example of themechanism of thickening a resist pattern to be thickened by using aresist pattern thickening material according to the present invention,and showing the state where the resist pattern thickening material isapplied over the surface of the resist pattern to be thickened.

FIG. 2 is a schematic diagram for explaining one example of themechanism of thickening a resist pattern to be thickened by using aresist pattern thickening material according to the present invention,and showing the state where the resist pattern thickening materialinfiltrates into the surface of the resist pattern to be thickened.

FIG. 3 is a schematic diagram for explaining one example of themechanism of thickening a resist pattern to be thickened by using aresist pattern thickening material according to the present invention,and showing the state where the resist pattern is thickened by theresist pattern thickening material, thereby forming a resist pattern.

FIG. 4 is a schematic diagram for explaining an example of a process forforming a resist pattern according to the present invention, and showingthe state where a resist layer is formed.

FIG. 5 is a schematic diagram for explaining an example of a process forforming a resist pattern according to the present invention, and showingthe state where the resist layer is subjected to patterning, therebyforming a resist pattern to be thickened.

FIG. 6 is a schematic diagram for explaining an example of a process forforming a resist pattern according to the present invention, and showingthe state where the resist pattern thickening material is applied overthe surface of the resist pattern to be thickened.

FIG. 7 is a schematic diagram for explaining an example of a process forforming a resist pattern according to the present invention, and showingthe state where a mixing is occurred at the vicinity of the surface ofthe resist pattern to be thickened and the resist pattern thickeningmaterial infiltrates into the resist pattern to be thickened.

FIG. 8 is a schematic diagram for explaining an example of a process forforming a resist pattern according to the present invention, and showingthe state where the resist pattern thickening material is developed.

FIG. 9 is a schematic diagram for explaining an example of a process forproducing a semiconductor device according to the present invention, andshowing the state where an interlayer insulating film is formed on asilicon substrate.

FIG. 10 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where a titanium film is formed on the interlayerinsulating film.

FIG. 11 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where a resist film is formed on the titanium filmand a hole pattern is formed on the titanium film.

FIG. 12 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where the hole pattern is also formed on thetitanium film.

FIG. 13 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where a copper film is formed on the interlayerinsulating film having the hole pattern.

FIG. 14 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where the copper is removed from the layer on thehole pattern of the interlayer insulating film.

FIG. 15 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where an interlayer insulating film is formed onthe copper plug formed inside of the hole pattern, and on the interlayerinsulating film.

FIG. 16 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where a hole pattern is formed on the interlayerinsulating film as a surface layer and a copper plug is formed therein.

FIG. 17 is a schematic diagram for explaining an example of a processfor producing a semiconductor device according to the present invention,and showing the state where a three-layered wiring is formed.

FIG. 18 is a top view for explaining a FLASH EPROM which is one exampleof a semiconductor device according to the present invention.

FIG. 19 is a top view for explaining a FLASH EPROM which is anotherexample of a semiconductor device according to the present invention.

FIG. 20 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention.

FIG. 21 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 20.

FIG. 22 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 21.

FIG. 23 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 22.

FIG. 24 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 23.

FIG. 25 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 24.

FIG. 26 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 25.

FIG. 27 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 26.

FIG. 28 is a cross-sectional schematic diagram for explaining a processfor producing the FLASH EPROM which is an example of the process forproducing a semiconductor device according to the present invention, andshowing a step after the step shown in FIG. 27.

FIG. 29 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is another example of theprocess for producing a semiconductor device according to the presentinvention.

FIG. 30 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is another example of theprocess for producing a semiconductor device according to the presentinvention, and showing a step after the step shown in FIG. 29.

FIG. 31 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is another example of theprocess for producing a semiconductor device according to the presentinvention, and showing a step after the step shown in FIG. 30.

FIG. 32 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is yet another example ofthe process for producing a semiconductor device according to thepresent invention.

FIG. 33 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is yet another example ofthe process for producing a semiconductor device according to thepresent invention, and showing a step after the step shown in FIG. 32.

FIG. 34 is a cross-sectional schematic diagram for explaining theprocess for producing the FLASH EPROM which is yet another example ofthe process for producing a semiconductor device according to thepresent invention, and showing a step after the step shown in FIG. 33.

FIG. 35 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head.

FIG. 36 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 35.

FIG. 37 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 36.

FIG. 38 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 37.

FIG. 39 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 38.

FIG. 40 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 39.

FIG. 41 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 40.

FIG. 42 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 41.

FIG. 43 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 42.

FIG. 44 is a cross-sectional schematic diagram for explaining an examplein which a resist pattern, which has been thickened by using the resistpattern thickening material according to the present invention, isapplied to the fabricating of a recording head, and showing a step afterthe step shown in FIG. 43.

FIG. 45 is a plan view showing an example of the recording headfabricated by the processes of FIGS. 35 to 44.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

-Resist Pattern Thickening Material-

The resist pattern thickening material according to the presentinvention contains at least a resin and, in addition, may contain abasic substance, crosslinking agent, surfactant, water-soluble cycliccompound, organic solvent, phase transfer catalyst, polyhydric alcoholhaving at least two hydroxyl groups, depending on the requirements, andalso it may contain additional components.

The resist pattern thickening material according to the presentinvention preferably exhibits a pH value of above 7 and not over 14(7<pH≦14) before coating on a resist pattern, more preferably is 8 ormore and 11 or less (8≦pH≦11). The resist pattern thickening materialaccording to the present invention exhibits a pH value of above 7 andnot over 14 (7<pH≦14) at coating on the resist pattern or after thecoating, preferably is 8 or more and 11 or less (8≦pH≦11).

When the pH value of the resist pattern thickening material is 7 orless, the resist pattern thickening material is likely to lack storagestability, and also the thickening level of resist patterns may changedepending on the environmental conditions such as temperature andatmosphere. On the contrary, when the pH value is above 7 and not over14, such problems may be suppressed, the resist pattern thickeningmaterial shows superior storage stability and can thicken resistpatterns uniformly, constantly and precisely regardless of the variousenvironmental conditions such as temperature and atmosphere, or long orshort storage period.

The resist pattern thickening material according to the presentinvention preferably contains a basic substance. Preferably, theexistence of basic substance may maintain the pH of the resist patternthickening material in alkaline condition by neutralizing even when afree acid generates during the storage, and also may maintain the pH atcoating on the resist pattern or after the coating in alkaline conditionby neutralizing, thus the resist pattern thickening material and theresist pattern can interact each other by a reaction in which acid doesnot intervene, that is, the resist pattern thickening material and theresist pattern may be interacted under other than acid-based reactionthat tends to provide unstable factors. As a result, the resist patterncan be thickened properly and uniformly regardless of various species orsizes of the resist pattern thickening material i.e. independently withthese factors.

-Basic Substance-

The basic substance may be properly selected depending on theapplication. For example, the above described crosslinking agent,surfactant, water-soluble cyclic compound, organic solvent, phasetransfer catalyst, and polyhydric alcohol having at least two hydroxylgroups may also be the basic substance; preferably, a proper basicsubstance other than these components is employed independently.

Existence of the basic substance in the resist pattern thickeningmaterial may afford advantages such as easy pH adjustment of the resistpattern thickening material and superior storage stability.

Preferably, the basic substance is at least one selected from the groupconsisting of amines, amides, imides, quaternary ammonium salts, andderivatives of the compounds. These compounds may afford the advantagessuch as easy pH adjustment of the resist pattern thickening material andsuperior storage stability in particular.

Examples of amine include chain-like amines, cyclic amines, aromaticamines, and alcohol amines such as hexylamine, heptylamine, octylamine,nonylamine, decylamine, aniline, 2-methylaniline, 3-methylaniline,4-methylaniline, 4-nitroaniline, 1-naphthylamine, 2-naphthylamine,ethylenediamine, tetramethylenediamine, hexamethylenediamine,4-4′-diamino-1,2-diphenylethane,4-4′-diamino-3,3′-dimethyldiphenylethane,4-4′-diamino-3,3′-diethyldiphenylethane, dibutylamine, dipentylamine,dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine,N-methylaniline, piperidine, diphenylamine, trimethylamine,triethylamine, tripropylamine, tributylamine, tripentylamine,trihexylamine, triheptylamine, trioctylamine, trinonylamine,tridecylamine, methylbutylamine, methyldipentylamine,methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine,methyldioctylamine, methyldinonylamine, methyldidecylamine,ethyldibutylamine, ethyldipentylamine, ethyldihexylamine,ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine,ethyldidecylamine, tris[2-(2-methoxyethoxy)ethyl]amine,N,N-dimethylaniline, imidazole, pyridine, 4-methylpyridine,4-methylimidazole, bipyridine, 2,2′-dipyridylamine, di-2-pyridylketone,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,3-di(4-pyridyl)propane, 1,2-di(2-pyridyl)ethylene,1,2-di(4-pyridyl)ethylene, 1,2-bis(4-pyridyloxy)ethane,4,4′-dipyridylsulfide, 4,4′-dipyridyldisulfide, 2,2′-dipicolylamine,3,3′-dipicolylamine, N-methyl-2-pyrrolidone, benzylamine, diphenylamine,monoethanolamine, diethanolamine, triethanolamine,2-(2-aminoethoxy)ethanol, N,N-dimethylethanolamine,N,N-diethylethanolamine, N,N-dibutylethanolamine, N-methylethanolamine,N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine,monoisopropanolamine, diisopropanolamine, and triisopropanolamine.

Examples of the amide include pentano-4-lactam, ε-caprolactam,succinamide, phthalamide, and cyclohexane carboxamide. Examples of theimide include succinimide, phthalimide, and cyclohexane dicarboxylicacid imide.

Examples of the quaternary ammonium salt include tetramethyl ammoniumhydroxide, tetraethyl ammonium hydroxide, tetraisopropyl ammoniumhydroxide, tetrabutylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, and trimethylphenyl ammonium hydroxide.These basic compounds may be used alone or in combination.

The content of the basic compounds in the resist pattern thickeningmaterials is not particularly limited, and may be properly selecteddepending on species and/or amount of the resin, crosslinking agent,surfactant or the like; the content is preferably 0.001 to 50% by mass,more preferably is 0.1 to 10% by mass.

When the content of the basic compounds is less than 0.001% by mass, theeffects due to the addition of the basic compound may not besignificant, thus pH at or after coating of the resist patternthickening material on the resist pattern may be outside of above 7 andnot over 14; on the other hand, the content of above 50% by mass may notprovide a satisfactory effect from such higher amount of basic compound.

Preferably, resist pattern thickening material is water-soluble oralkaline-water soluble, since such solubility may bring about easydevelopment and the like.

The solubility in water may be properly selected depending on theapplication, a preferable example is that 0.1 gram or more of resistpattern thickening material is soluble into 100 grams of water at 25° C.

Also, the solubility in alkaline-water may be properly selecteddepending on the application, a preferable example is that 0.1 gram ormore of resist pattern thickening material is soluble into 100 grams of2.38% by mass tetramethyl ammonium hydroxide (TMAH) aqueous solution.

The resist pattern thickening material is allowable even in a state ofcolloid or emulsion, preferably is water-soluble.

-Resin-

The resin is not particularly limited and may be properly selecteddepending on the application. The resin is preferably water-soluble oralkali-soluble, and more preferably is able to undergo a crosslinkingreaction or able to mix with a water-soluble crosslinking agent.

Each molecule of the resin preferably comprises two or more polar groupsin view of exhibiting an excellent water-solubility oralkali-solubility.

The polar group is not particularly limited and may be properly selecteddepending on the application. Examples thereof include hydroxyl group,amino group, sulfonyl group, carbonyl group, carboxyl group, derivativesthereof, and the like. The polar group may be contained singly or two ormore polar groups may be contained in combination.

When the resin is water-soluble, the water-soluble resin preferablyexhibits water solubility of 0.1 g or more in 100 g of water at 25° C.,and more preferably exhibits water solubility of 0.3 g or more in 100 gof water at 25° C., and particularly preferably exhibits watersolubility of 0.5 g or more in 100 g of water at 25° C.

Examples of the water-soluble resin include polyvinyl alcohol, polyvinylacetal, polyvinyl acetate, polyacrylic acid, polyvinyl pyrolidone,polyethyleneimine, polyethylene oxide, styrene-maleic acid copolymer,polyvinylamine, polyallylamine, oxazoline group-containing water-solubleresins, water-soluble melamine resins, water-soluble urea resins, alkydresins, sulfonamide resins, and the like.

When the resin is alkaline-water soluble, the alkaline-water solubleresin preferably exhibits alkaline-water solubility of 0.1 g or more in100 g of 2.38% by mass tetramethyl ammonium hydroxide (TMAH) aqueoussolution at 25° C., and more preferably exhibits alkaline-watersolubility of 0.3 g or more in 100 g of 2.38% by mass TMAH aqueoussolution at 25° C., and particularly preferably exhibits alkaline-watersolubility of 0.5 g or more in 100 g of 2.38% by mass TMAH aqueoussolution at 25° C.

Examples of the alkali-water soluble resin include novolak resins,vinylphenol resins, polyacrylic acids, polymethacrylic acids, polyp-hydroxyphenylacrylate, poly p-hydroxyphenylmethacrylate, copolymerthereof, and the like.

A resin may be used singly or in combination. Among these, polyvinylalcohol, polyvinyl acetal, polyvinyl acetate and the like arepreferable. The resin more preferably contains polyvinyl acetal at 5% bymass to 40% by mass.

Preferably, the resin contains a cyclic structure at least at a portionthereof. Such a cyclic structure may afford an advantage that excellentetching-resistance properties can be imparted to the resist patternthickening material.

In the present invention, the resin having a cyclic structure at leastat a portion thereof may be used singly or in combination.

The resin having a cyclic structure at a portion thereof is notparticularly limited and may be properly selected depending on theapplication, those capable of causing a crosslinking reaction arepreferable. Suitable examples thereof include polyvinyl arylacetalresins, polyvinyl arylether resins, polyvinyl arylester resins, andderivatives thereof, preferably, at least one is selected therefrom.From the standpoint of exhibiting water solubility or alkaline-watersolubility to an appropriate degree, such a resin that contains anacetyl group is more preferable.

The polyvinyl arylacetal resins are not particularly limited and may beproperly selected depending on the application. Examples thereof includeβ-resorcine acetal and the like.

The polyvinyl aryl ether resins are not particularly limited and may beproperly selected depending on the application. Examples thereof include4-hydroxybenzyl ether and the like.

The polyvinyl aryl ester resins are not particularly limited and may beproperly selected depending on the application. Examples thereof includebenzoate and the like.

The method for producing the polyvinyl arylacetal resins is notparticularly limited and may be properly selected depending on theapplication. Suitable examples are conventional methods by making use ofa polyvinyl acetal reaction, or the like. For example, polyvinylalcohol, and aldehyde in an amount needed stoichiometrically for thepolyvinyl alcohol undergo an acetalizing reaction in the presence of anacid catalyst. Specific examples are disclosed in U.S. Pat. Nos.5,169,897 and 5,262,270, Japanese Patent Application Laid-Open (JP-A)No. 5-78414, and the like.

The method of producing the polyvinyl aryl ether resins is notparticularly limited and may be properly selected depending on theapplication. Examples thereof are a copolymerization reaction of acorresponding vinyl aryl ether monomer and vinyl acetate; an etherizingreaction of polyvinyl alcohol and an aromatic compound having ahalogenated alkyl group in the presence of a basic catalyst (the ethersynthesizing reaction by Williamson); and the like. Specific examplesare disclosed in JP-A Nos. 2001-40086, 2001-181383, 6-116194, and thelike.

The method of producing the polyvinyl aryl ester resins is notparticularly limited and may be properly selected depending on theapplication. Examples thereof are a copolymerization reaction of acorresponding vinyl arylester monomer and vinylacetate; an esterizingreaction of polyvinyl alcohol and an aromatic carboxylic acid halidecompound in the presence of a basic catalyst; and the like.

The cyclic structure in the resin having a cyclic structure at a portionthereof, is not particularly limited and may be properly selecteddepending on the application. Examples thereof are monocyclic structuresuch as benzene, polycyclic structure such as bisphenol, condensed ringsuch as naphthalene, specifically, aromatic compounds, alicycliccompounds, heterocyclic compounds, and the like are preferred. In theresin having a cyclic structure at a portion thereof, a cyclic structuremay be used singly or in combination.

Examples of the aromatic compound include polyhydroxy phenol compounds,polyphenol compounds, aromatic carboxylic acid compounds, naphthalenepolyhydroxy compounds, benzophenone compounds, flavonoid compounds,porphin, water-soluble phenoxy resins, aromatic-containing water-solubledyes, derivatives thereof, glycosides thereof, and the like. Thearomatic compound may be used singly or in combination.

Examples of the polyhydric phenol compounds are resorcinol,resorcin[4]arene, pyrogallol, gallic acid, derivatives and glycosidesthereof, and the like.

Examples of the polyphenol compounds include catechin, anthocyanidin(pelargonidin-type (4′-hydroxy), cyanidin-type (3′,4′-dihydroxy),delphinidin-type (3′,4′,5′-trihydroxy)), flavan-3,4-diol,proanthocyanidin, and the like. Examples of the aromatic carboxylic acidcompounds include salicylic acid, phthalic acid, dihydroxy benzoic acid,tannin, and the like.

Examples of the naphthalene polyhydroxy compounds include naphthalenediol, naphthalene triol, and the like. Examples of the benzophenonecompounds include alizarin yellow A, and the like. Examples of theflavonoid compounds include flavone, isoflavone, flavanol, flavonone,flavonol, flavan-3-ol, aurone, chalcone, dihydrochalcone, quercetin, andthe like.

Examples of the alicyclic compound include polycycloalkanes,cycloalkanes, fused rings, derivatives and glycosides thereof, and thelike. These may be used singly or in combination.

Examples of the polycycloalkane include norbornane, adamantane,norpinane, sterane, and the like. Examples of the cycloalkane includecyclopentane, cyclohexane, and the like. Examples of the fused ringinclude steroids and the like.

Suitable examples of the heterocyclic compound include anitrogen-containing cyclic compound such as pyrrolidine, pyridine,imidazole, oxazole, morpholine, pyrrolidone, and the like; and anoxygen-containing cyclic compound such as furan, pyran, saccharides suchas pentose and hexose; and the like.

Preferable examples of the resin having a cyclic structure at a portionthereof are ones having at least one selected from the functional groupssuch as, for instance, hydroxyl group, cyano group, alkoxyl group,carboxyl group, amino group, amide group, alkoxycarbonyl group,hydroxyalkyl group, sulphonyl group, acid anhydride group, lactonegroup, cyanate group, and ketone group etc.; and the saccharicderivatives from the viewpoint of water-solubility. The one having atleast one functional group selected from the hydroxyl group, aminogroup, sulphonyl group, carboxyl group, and their derivatives is morepreferable.

The molar content ratio of the cyclic structure in the resin having acyclic structure at a portion thereof, is not particularly limited aslong as it does not affect the etching resistance, and may be properlyselected depending on the application. In the case where high etchingresistance is needed, it is preferably 5 mol % or more, and morepreferably, 10 mol % or more.

The molar content ratio of a cyclic structure in the resin having acyclic structure at a portion thereof, can be measured by means of NMRetc.

The content of the resins, including the resin having a cyclic structureat a portion thereof, in the resist pattern thickening material may beproperly selected depending on the type and content of the basicsubstance or basic material and the like.

-Crosslinking Agent-

The crosslinking agents are not particularly limited and may be properlyselected depending on the application. Preferable examples are ones thathave water-solubility and cause crosslinking by heat or acid, and morepreferable is an amino crosslinking agent.

Preferable examples of the amino crosslinking agent include melaminederivatives, urea derivatives, and uril derivatives and the like. Thesemay be used alone or in combination.

Examples of the urea derivatives include urea, alkoxymethylene urea,N-alkoxymethylene urea, ethylene urea, ethylene urea carboxylic acid,their derivatives and the like. Examples of the melamine derivatives arealkoxymethyl melamine, their derivatives and the like. Examples of theuril derivatives are benzoguanamine, glycol uril, their derivatives andthe like.

The content of the crosslinking agents in the resist pattern thickeningmaterial depends on the type and content etc. of the resin etc., so thatit is impossible for it to be prescribed unconditionally. It may beproperly selected depending on the application.

-Surfactant-

The surfactants are not particularly limited and may be suitablyselected in accordance with the purpose. Examples thereof includenonionic surfactants, cationic surfactants, anionic surfactants,ampholytic surfactants and the like. These may be used singly or incombination. A suitable one among them is a nonionic surfactant from thepoint that it does not contain metallic ions.

Preferable examples of the nonionic surfactants are ones selected fromalkoxylate surfactants, fatty acid ester surfactants, amide surfactants,alcoholic surfactants, and ethylenediamine surfactants. The concreteexamples thereof include polyoxyethylene-polyoxypropylene condensationcompounds, polyoxy alkylene alkylether compounds, polyoxy ethylenealkylether compounds, polyoxy ethylene derivative compounds, sorbitanfatty acid ester compounds, glycerine fatty acid ester compounds,primary alcohol ethoxylate compounds, phenol ethoxylate compounds, nonylphenol ethoxylate compounds, octyl phenol ethoxylate compounds, laurylalcohol ethoxylate compounds, oleyl alcohol ethoxylate compounds, fattyacid ester, amide, natural alcohol, ethylenediamine, secondary alcoholethoxylate and the like.

The cationic surfactants are not particularly limited and may beproperly selected depending on the application. Examples thereof includealkyl cationic surfactants, amide quaternary cationic surfactants, esterquaternary cationic surfactants and the like.

The ampholytic surfactants are not particularly limited and may beproperly selected depending on the application. Examples thereof includeamine oxide surfactants, betaine surfactants and the like.

The content of the surfactants in the resist pattern thickening materialdepends on the type and content etc. of the resin and basic substance orbasic compound; the content may be properly selected depending on theapplication.

-Cyclic Structure-Containing Compound-

The cyclic structure-containing compound may be properly selected fromthose having a cyclic structure and an aqueous solubility depending onthe application without particular limitations. The aqueous solubilityis preferably 1 gram or more into 100 grams of water at 25° C., morepreferably is 3 grams or more into 100 grams of water at 25° C., andmost preferably is 5 grams or more into 100 grams of water at 25° C.

The cyclic structure-containing compound involved in the resist patternthickening material may significantly and advantageously increase theetching resistance of the resulting pattern owing to the cyclicstructure in the cyclic structure-containing compound.

Suitably examples of the cyclic structure-containing compound arearomatic compounds, alicyclic compounds, and heterocyclic compounds,preferably are aromatic compounds. These may be utilized alone or incombination.

Examples of the aromatic compound include polyhydroxy phenol compounds,polyphenol compounds, aromatic carboxylic acid compounds, naphthalenepolyhydroxy compounds, benzophenone compounds, flavonoid compounds,porphins, water-soluble phenoxy resins, aromatic-containingwater-soluble dyes, derivatives thereof, glycosides thereof, and thelike. The aromatic compounds may be utilized alone or in combination.

Examples of the polyhydric phenol compounds include resorcinol,resorcin[4]arene, pyrogallol, gallic acid, derivatives and glycosidesthereof, and the like.

Examples of the polyphenol compounds include catechin, anthocyanidin(pelargonidin-type (4′-hydroxy), cyanidin-type (3′,4′-dihydroxy),delphinidin-type (3′,4′,5′-trihydroxy)), flavan-3,4-diol,proanthocyanidin, and the like.

Examples of the aromatic carboxylic acid compounds include salicylicacid, phthalic acid, dihydroxy benzoic acid, tannin, and the like.Examples of the naphthalene polyhydroxy compounds include naphthalenediol, naphthalene triol, and the like. Examples of the benzophenonecompounds include alizarin yellow A, and the like. Examples of theflavonoid compounds include flavone, isoflavone, flavanol, flavonone,flavonol, flavan-3-ol, aurone, chalcone, dihydrochalcone, quercetin, andthe like.

Examples of the alicyclic compound include polycycloalkanes,cycloalkanes, fused rings, derivatives and glycosides thereof, and thelike. These may be used alone or in combination. Examples of thepolycycloalkane include norbornane, adamantane, norpinane, sterane, andthe like. Examples of the cycloalkane include cyclopentane, cyclohexane,and the like. Examples of the fused rings include steroids and the like.

Suitable examples of the heterocyclic compound include anitrogen-containing cyclic compound such as pyrrolidine, pyridine,imidazole, oxazole, morpholine, pyrrolidone, and the like; and anoxygen-containing cyclic compound such as furan, pyran, saccharides suchas pentose and hexose; and the like.

These cyclic structure-containing compounds may be used alone or incombination. Among these, the polyphenol compounds are preferable, inparticular catechin and resorcine are preferable.

Among cyclic structure-containing compounds, from the viewpoint ofwater-solubility, the one having two or more polar groups is preferable,the one having three or more is more preferable, and the one having fouror more is particularly preferable.

The polar group is not particularly limited and can be suitably selectedin accordance with the purpose. Examples thereof are a hydroxyl group, acarboxyl group, a carbonyl group, a sulfonyl group, and the like.

The content of the cyclic structure-containing compound in the resistpattern thickening material may be selected depending on the type andcontent etc. of the resin, crosslinking agent, and surfactants etc.

-Organic Solvent-

The organic solvent is not particularly limited and may be properlyselected depending on the application. Examples thereof include alcoholorganic solvents, linear ester organic solvents, cyclic ester organicsolvents, ketone organic solvents, linear ether organic solvents, cyclicether organic solvents, and the like.

When the resist pattern thickening material contains the abovementionedorganic solvent, the advantage is that the resin and the polyhydricalcohol having at least two of the hydroxyl groups and the crosslinkingagent may be improved in terms of the solubility in the resist patternthickening material.

Examples of the alcohol organic solvents include methanol, ethanol,propyl alcohol, isopropyl alcohol, butyl alcohol, and the like. Examplesof the linear ester organic solvents include ethyl lactate, propyleneglycol methyl ether acetate (PGMEA), and the like. Examples of thecyclic ester organic solvents include lactone organic solvents such asγ-butyrolactone, and the like. Examples of the ketone organic solventsinclude ketone organic solvents such as acetone, cyclohexanone, andheptanone, and the like.

Examples of the linear ether organic solvents include ethyleneglycoldimethylether, and the like. Examples of the cyclic ether organicsolvents include tetrahydrofuran, dioxane, and the like.

These organic solvents may be used alone or in combination. Among these,solvents having a boiling point of about 80 to 200° C. are preferablefrom the viewpoint of performance to thicken the resist patternprecisely.

The content of the organic solvents in the resist pattern thickeningmaterial can be decided according to the type and content etc. of theresin, basic substance or basic compound, crosslinking agent, andsurfactant etc.

-Phase Transfer Catalyst-

The phase transfer catalyst is not particularly limited and may beproperly selected depending on the application. Examples thereof includeorganic materials, preferably are basic materials.

When the resist pattern thickening material contains the phase transfercatalyst, an advantage may be obtained that the resist pattern isefficiently and uniformly thickened regardless of a material of theresist pattern. Therefore, through utilizing such resist patternthickening materials, the thickening effect of the resist pattern ishardly affected by materials of the resist pattern. Such effects of thephase transfer catalyst are not impaired, for instance, even if theresist pattern, which is the subject to be thickened with use of theresist pattern thickening material, contains an acid generating agent ornot.

The preferable phase transfer catalyst is the one havingwater-solubility, and the water-solubility is such that 0.1 g or morecan be dissolved in 100 g of water at temperature of 25° C.

Specific examples of the phase transfer catalyst include crown ether,azacrown ether, onium salt compounds, and the like.

The phase transfer catalyst may be used singly or in combination. Amongthese, onium salt compounds are preferable from the viewpoint of higherwater-solubility.

Examples of the crown ether and azacrown ether include 18-crown-6,15-crown-5, 1-aza-18-crown-6, 4,13-diaza-18-crown-6,1,4,7-triazacyclononane, and the like.

The onium salt compounds are not particularly limited and may beproperly selected depending on the application. The preferable examplesthereof include quarternary ammonium salts, pyridinium salts, thiazoliumsalts, phosphonium salts, piperazinium salts, ephedrinium salts, quiniumsalts, cinchonium salts, and the like.

Examples of the quarternary ammonium salt include tetrabutylammoniumhydrogensulfate, tetramethylammonium acetate, tetramethylammoniumchloride, and the like which are often used for synthetic organicagents. Examples of the pyridinium salt include hexadecylpyridiniumbromide, and the like. Examples of the thiazolium salt include3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride, and the like.Examples of the phosphonium salt include tetrabutylphosphonium chloride,and the like. Examples of the piperazinium salt include1,1-dimethyl-4-phenylpiperazinium, and the like. Examples of theephedrinium salt include (−)-N,N-dimethylephedrinium bromide, and thelike.

Examples of the quinium salt include N-benzylquininium chloride, and thelike. Examples of the cinchonium salt include N-benzylcinchoniniumchloride, and the like.

The content of the phase transfer catalyst in the resist patternthickening material depends on the type and content etc. of the resinetc., so that it is impossible to define definitely, but it can besuitably selected according to the type and content etc. For instance,10000 ppm or less is preferable, 10 to 10000 ppm is more preferable, 10to 5000 ppm is further preferable, and 10 to 3000 ppm is particularlypreferable.

When the content of the phase transfer catalyst is 10000 ppm or less,the advantageous point is that the resist pattern such as a line patternetc. can be thickened independent of the size.

The content of the phase transfer catalyst can be measured with use of,for instance, liquid chromatography.

-Polyhydric Alcohol Having at Least Two Hydroxyl Groups-

The polyhydric alcohol having at least two hydroxyl groups is notparticularly limited and may be properly selected depending on theapplication. Examples thereof include saccharides, derivatives ofsaccharides, glycosides, naphthalene polyhydric alcohol compound, andthe like.

The saccharides may be properly selected depending on the applicationwithout particular limitations. Examples thereof include pentose,hexose, and the like. The concrete examples of the saccharides includearabinose, fructose, galactose, glucose, ribose, saccharose, maltose,and the like.

The derivatives of saccharides may be properly selected depending on theapplication without particular limitations. Preferable examples thereofare amino sugar, saccharic acid, deoxysuga, sugar alcohol, glycal,nucleoside, and the like.

The glycosides may be properly selected depending on the applicationwithout particular limitations. Preferable examples thereof includephenolic glycosides, and the like. Preferable examples of phenolicglycosides are salicin, arbutin, 4-aminophenyl galactopyranoside, andthe like.

Examples of the naphthalene polyhydroxy compounds include naphthalenediol, naphthalene triol, and the like.

These may be used alone or in combination. Among these, the one havingaromaticity is preferable from the viewpoint of being possible to addetching resistance to the resist pattern thickening material. Glycosidesare preferable, and phenolic glycosides are more preferable.

The content of polyhydric alcohol having at least two hydroxyl groups inthe resist pattern thickening material may be properly selecteddepending on the application without particular limitations. Forinstance, the preferable amount is 0.001 to 50 parts by mass base on thetotal amount of the resist pattern thickening material, and the morepreferable amount is 0.1 to 10 parts by mass.

When the content of the polyhydric alcohol having at least two hydroxylgroups is less than 0.001 parts by mass, the amount of increasedthickness of the resist pattern thickening material may depend on theresist pattern size. On the other hand, when it exceeds 10 parts bymass, a part of the resist pattern is possibly dissolved depending onthe resist material.

-Other Components-

The other components are not particularly limited as long as they do notinterfere with the effects of the present invention, and may be properlyselected depending on the application. All types of known additives, forinstance, thermal acid generating agents, quenchers such as amine type,amide type, ammonium chloride type quenchers etc. may be given as theexamples.

-Application of Resist Pattern Thickening Material-

In the application of the resist pattern thickening materials accordingto the present invention, they are coated on resist patterns to bethickened.

The resist materials of resist patterns to be thickened may be properlyselected from conventional resist materials including negative-type andpositive-type without particular limitations. Examples of the resistmaterials include g-line resists, i-line resists, KrF resists, ArFresists, F2 resists, electron beam resists, and the like that can bepatterned by means of g-line, i-line, KrF excimer laser, ArF excimerlaser, F2 excimer laser, electron beam or the like, which may be or maynot be chemically amplified type. Among these, KrF resists, ArF resists,and resists containing acrylic resins are preferable; in addition, ArFresists and resists containing acrylic resin are preferable from viewpoint that they are demanded in terms of improvement in resolution limitfor finer patterning and increase of throughput.

Preferably, the resist pattern exhibits a pH value of below 7 prior tothickening from the view point of consistent and stable thickening.

The specific examples of the resist pattern material include novolakresists, PHS resists, acrylic resists, cyclo olefin-maleic acidanhydrate (COMA) resists, cyclo olefin resists, hybrid resists such asalicyclic acrylic-COMA copolymer and the like. These resists may bemodified by fluorine.

The method for coating the resist pattern thickening material is notparticularly limited and can be selected from the known methods forcoating. Examples thereof are roller coating method, dip coating method,spray coating method, bar coating method, kneader coating method,curtain coating method, and the like. Particularly, a spin coatingmethod is preferable. In the case of the spin coating method, thecondition is, for instance, a rotation speed of about 100 to 10000 rpm,and the preferable rotation speed is 80 to 5000 rpm. The preferableperiod is about 1 second to 10 minutes, and more preferably is 1 to 90seconds.

The coating thickness at the time of the coating is usually about 10 to1000 nm, and the preferable thickness is about 100 to 500 nm.

At the time of the coating, the surfactant may be coated separatelybefore coating the resist pattern thickening material in stead of addingthe surfactant into the resist pattern thickening material.

Pre-baking or warming-drying of the coated resist pattern thickeningmaterial during or before the coating is a preferable method because itefficiently generates mixing or infiltrating of the resist patternthickening material into the resist pattern at the interface between theresist pattern and the resist pattern thickening material.

The condition and method for pre-baking or warming-drying are notparticularly limited and can be suitably selected according to thepurpose. For instance, the number of times of it may be once or twotimes or more. In the case of two times or more, the temperature ofpre-baking may be constant or different respectively. When it isconstant as mentioned above, the preferable temperature is about 60 to150° C., and 70 to 120° C. is more preferable. The preferable period isabout 30 to 300 seconds, and more preferably is 40 to 100 seconds.

The pre-baking is carried out by removing solvent, which may be carriedout according to conditions recommended by the manufacturer, forexample, independently with thickening the resist pattern.

Preferably, coating baking or mixing baking of the resist patternthickening material is carried out after the pre-baking orwarming-drying, because the mixing or infiltrating progressesefficiently at the interface between the resist pattern and the resistpattern thickening material.

The conditions for the coating baking or mixing baking may be properlyselected depending on the application; typically the coating baking iscarried out at a temperature higher than that of the pre-baking orwarming-drying. The temperature at the coating baking is about 60 to150° C., more preferable temperature is 90 to 130° C. The period isabout 30 to 300 seconds, and the preferable period is 40 to 100 seconds.

When the temperature at coating baking or mixing baking is lower than60° C., the coating baking or mixing baking may not progressefficiently, on the other hand, when the temperature is above 150° C.,the shape of the resist pattern may be deformed by the highertemperature. The reaction without acid is a thermal reaction, thus thethickened or swelled level of the resist pattern tend to increase whenthe temperature rises.

Preferably, developing is carried out on the coated resist patternthickening material after the coating baking or mixing baking is carriedout. In this case, the portions of coated resist pattern thickeningmaterial where the interaction or mixing is not induced or isinsufficient with the resist pattern can be successfully dissolved andremoved to thereby develop the thickened resist pattern.

The development may be water development, development using weaklyalkaline solution, or a combination thereof. Water development ispreferable since the development can be carried out efficiently and atlower cost.

The development produces a thickened resist pattern, in which the resistpattern is thickened by the resist pattern thickening material. In thethickened resist pattern, the space pattern formed by the thickenedresist pattern is finer and more precise than that of un-thickenedresist pattern. Therefore, the thickened resist pattern can lead tofiner and more precise electrical writings of semiconductor devices byapplying it as a masking pattern at etching etc.

The resist pattern thickening material according to the presentinvention may be properly applied to a process for forming a resistpattern according to the present invention, and also be properly appliedto a process for producing semiconductor device according to the presentinvention.

(Process for Forming Resist Pattern and Process for ProducingSemiconductor Device)

The process for forming a resist pattern comprises coating the resistpattern thickening material according to the present invention on aresist pattern, thickening the resist pattern, and the others dependingto the requirements.

The process for producing a semiconductor device according to thepresent invention comprises forming a thickened resist pattern,patterning, and the others depending to the requirements.

The semiconductor device according to the present invention is producedby the process for producing a semiconductor device according to thepresent invention.

The semiconductor device according to the present invention will beapparent through the explanations as to the process for producing asemiconductor device according to the present invention.

-Formation of Thickened Resist Pattern-

In forming the thickened resist pattern, a resist pattern is formed on aworked surface, the resist pattern thickening material according to thepresent invention is coated on the resist pattern by the processaccording to the present invention, thereby thickening the resistpattern to form a thickened resist pattern.

The formation of the thickened resist pattern, which corresponding tothe process for forming a resist pattern according to the presentinvention, will be apparent through the explanations as to the formationof the thickened resist pattern.

-Workpiece-

The workpiece or substrate may be properly selected depending on theapplication, and may be a substrate of semiconductor device such assilicon wafer, interlayer insulating film, film of wiring material,various oxide films, or the like.

-Formation of Resist Pattern-

The process for forming the resist pattern may be properly selecteddepending on the application; for example, forming a coated layer of aconventional resist material by a conventional coating process, thenirradiating the coated layer, thereby obtaining a resist pattern with anintended design. Further, baking may be optionally carried out after theirradiation.

The irradiating beam or light may be properly selected depending on theresist material; example thereof include g-line, i-line, KrF excimerlaser, ArF excimer laser, F2 excimer laser beam, electron beams, and thelike.

The size and thickness etc. of the resist pattern may be properlyselected depending on the application; the thickness is 2 to 200 μm ingeneral, and may be determined by the workpiece, etching conditions etc.

By the way, baking under vacuum condition (hereinafter, referring to as“vacuum baking”) may be optionally carried out after the formation ofthe resist pattern in order to remove the residual acid in the resistpattern. The temperature at the vacuum baking may be properly selecteddepending on the application, for example, 60 to 150° C. is preferable,more preferably is 80 to 130° C.

When the temperature is below 60° C., the residual acid in the resistpattern may not be removed sufficiently, on the contrary, when thetemperature is above 150° C., the shape of the resist pattern may bedeformed by the higher temperature.

The vacuum level at the vacuum baking may be properly selected dependingon the application, for example, preferably is 50 torr or less, morepreferably is 10 torr or less.

When the vacuum level is above 50 torr, the effect to evaporate theresidual acid in the resist pattern may not be significant and thus theresidual acid may not be removed sufficiently.

The period of the vacuum baking may be properly selected depending onthe application, for example, preferably is 10 to 300 seconds, morepreferably is 30 to 120 seconds.

When the period is less than 10 seconds, the effect to evaporate theresidual acid in the resist pattern may not be significant and thus theresidual acid may not be removed sufficiently. When the period exceeds300 seconds, the expected effect may not appear and the processingperiod may not be shortened.

The vacuum baking may be carried out by means of properly selectedconventional apparatuses such as a vacuum heating apparatus.

The resist pattern thickening material may be that of the presentinvention. The coating process of the resist pattern thickening materialmay be that described above. Through the forming of the thickened resistpattern, the resist pattern is thickened to obtain a thickened resistpattern.

Preferably, the resulting thickened resist pattern represent properlyhigh etching resistance. Preferably, the etching rate (nm/min) of theresist pattern is equivalent to or greater than that of the resistpattern to be thickened. Specifically, when measuring under the samecondition, the ratio (resist pattern to be thickened/surface layer(mixing layer)) of the etching rate (nm/min) of the surface layer(mixing layer) to the etching rate (nm/min) of the resist pattern to bethickened is preferably 1.1 or more, and more preferably is 1.2 or more,and particularly preferably is 1.3 or more.

The etching rate (nm/min) can be measured by, for example, carrying outetching processing for a predetermined time by using a known etchingdevice, measuring the amount of film reduction of the sample, andcalculating the amount of film reduction per unit time.

The surface layer or mixing layer can suitably be formed by using theresist pattern thickening material according to the present invention.From the standpoint of improving the etching resistance, the surfacelayer or mixing layer preferably contains the cyclic structure, e.g., aresin having a cyclic structure at least on a portion thereof.

Whether or nor the surface layer contain the cyclic structure can beconfirmed by, for example, analyzing the IR absorption spectrum of thesurface layer.

Coating the resist pattern thickening material on the resist pattern,and allowing to interact or to mix with the resist pattern, then amixing layer appears at the surface of the resist pattern that is formedby the interaction between the resist pattern thickening material andthe resist pattern. Consequently, the resist pattern is thickenedcorresponding to the formation of the mixing layer, thus the thickenedresist pattern is formed.

At this stage, the resist pattern thickening material according to thepresent invention exhibits a pH value of above 7 and not over 14(7<pH≦14) at coating on the resist pattern or after the coating on theresist pattern. Accordingly, the resist pattern thickening material andthe resist pattern may be interacted by aforesaid non-acid reactionwithout the acid-based reaction that provides unstable factors.Consequently, uniform thickening effect may be derived without beingaffected by species or sizes of the resist pattern. The resist pattern,which is formed in this way, represents space patterns of which thediameter or width is smaller than the space patterns of resist patternprior to thickening. As a result, the space pattern formed by the resistpattern exceeds an exposure limit or resolution limit and can representfiner structures, in other words, the size of spaces such as pore andgroove of the resulting space pattern is smaller than the lower limit ofspace that can be patterned by the wavelength of available irradiationsources.

Accordingly, when patterning a resist pattern by means of ArF excimerlaser beam, and thickening the resist pattern by means of the resistpattern thickening material, the space pattern of resist formed by thethickened resist pattern can represent such fine and precise conditionsas those patterned by electron beam.

The process for forming a resist pattern according to the presentinvention will be explained will be explained with reference to theattached figures.

As shown in FIG. 1, resist pattern 3 is formed on the surface ofworkpiece or substrate 5, then resist pattern thickening material 1 isapplied or coated on the surface of resist pattern 3, and pre-bakingsuch as warming and drying is conducted optionally. Then, mixing orinfiltrating of resist pattern thickening material 1 into resist pattern3 occurs at the interface between resist pattern 3 and resist patternthickening material 1, thus surface layer or mixing layer 10 a is formedby mixing or infiltrating at the interface between inner layer resistpattern 10 b or resist pattern 3 and resist pattern thickening material1 as shown in FIG. 2.

Even if residual acid exist in resist pattern 3 at this stage, resistpattern thickening material 1 represents a pH value of above 7 and notover 14 or less at coating or after coating on resist pattern 3;therefore, the residual acid can be neutralized and resist pattern 3 andresist pattern thickening material 1 can be interacted or mixed in acondition without acid. That is, since resist pattern 3 and resistpattern thickening material 1 can be interacted or mixed by the non-acidreaction, thickening of resist pattern 3 can be performed stably anduniformly without being significantly affected by environmental changessuch as temperature and humidity.

Then, thickened resist pattern 10 is formed or developed with uniformthickening, by dissolving and removing the portions with no or lessinteraction or mixing with resist pattern 3 in resist pattern thickeningmaterial 1 coated on resist pattern 3, through developing process toremove water-soluble portions. The developing may be of water oralkaline developing liquid.

Thickened resist pattern 10 possesses surface layer or mixing layer 10 aformed by mixing of resist pattern thickening material 1 on inner layerresist pattern 10 b or resist pattern 3. The thickened resist pattern 10is swelled by the thickness of surface layer or mixing layer 10 acompared to resist pattern 3; therefore, the sizes of space pattern,e.g. distance between adjacent thickened resist patterns 10 and aperturesize of hole pattern formed in thickened resist pattern, are smallerthan those of resist pattern prior to thickening.

Accordingly, the space pattern formed by the resist pattern can be finerthan the exposure limit or resolution limit of the exposure device toform resist pattern. For example, when exposing by means of ArF excimerlaser beam, the space pattern can be as fine as that by means ofelectron beam. Thus, the space pattern formed by thickened resistpattern 10 is finer and more precise than the space pattern formed byresist pattern 3 b.

The surface layer or mixing layer 10 a of thickened resist pattern 10 isformed by resist pattern thickening material 1. When resist patternthickening material 1 contains a cyclic structure as described above,the resulting resist pattern thickening material 1 may exhibit superioretching resistance even if the material of resist pattern or innerresist pattern 10 b is relatively poor in etching resistance.

The space pattern formed by thickened resist pattern may be line-spacepattern, hole pattern such as for contact hole, and trench or groovepattern, and the like.

The thickened resist pattern may be utilized as mask patterns, reticlepatterns, or the like, and may be applied for fabricating of functionalparts such as, recording heads, LCDs (liquid crystal displays), PDPs(plasma display panels), SAW filters (surface acoustic wave filters),and the like; optical parts used in connecting optical wiring; fineparts such as microactuators and the like; semiconductor devices; andthe like, in particular may be employed in the pattering processdescribed later.

-Patterning-

In the patterning, etching is carried out using the thickened resistpattern as a mask to pattern the workpiece surface.

The method of etching is not particularly limited, and can beappropriately selected from conventional methods depending on theapplication; dry etching is a suitable process. The etching conditionsare not particularly limited and may be properly selected depending onthe application.

Preferably, the residual resist pattern is peeled and removed in thepatterning process depending on the requirements. The specific way topeel and remove may be properly selected depending on the application; away using an organic solvent is exemplified.

Using the patterning process, various semiconductor devices such asflash memories, DRAM (Dynamic Random Access Memory), FRAM (FerroelectricRandom Access Memory), and the like may be produced efficiently.

The resulting semiconductor devices according to the present inventionproduced by the process for producing semiconductor devices according tothe present invention possesses uniform and fine pattern such as wiringand displays high performance, thus may be utilized in various fields.

Hereinafter, the present invention will be described specifically by wayof Examples, but it should be understood that the present invention isnot limited thereto.

EXAMPLE 1

-Preparation of Resist Pattern Thickening Material-

Resist pattern thickening materials were prepared and evaluated asfollows:

As shown in Table 1, 16 grams of polyvinyl acetal resin (KW-3, bySekisui Chemical Co., Ltd.) as the resin; 0.29 gram of phenolethoxylatesurfactant (non-ionic surfactant PC-6, by Asahi Denka Co, Ltd.) or 0.25gram of primary alcohol ethoxylate surfactant (non-ionic surfactantTN-80, by Asahi Denka Co., Ltd.) as the surfactant; 1.35 grams or 1.16grams of tetramethoxymethylglycol uril (Nikarrac, by Sanwa Chemical Co.,Ltd.) as the crosslinking agent; a mixed solution of de-ionized waterand isopropyl alcohol as the organic solvent (de-ionized water:isopropylalcohol=98.6 g:0.4 g) or a mixed solution of de-ionized water and 2.38%by mass tetramethylammonium hydroxide as the organic solvent (de-ionizedwater:2.38% by mass tetramethylammonium hydroxide=90 g:3 g) wereutilized and resist pattern thickening materials A to I were prepared asshown in Table 1.

The pH values of the resulting resist pattern thickening materials of Ato I were measured and indicated in Table 1. The resist patternthickening materials of A to H are examples of the present invention,and the resist pattern thickening material of I is a comparativeexample.

TABLE 1 thickening crosslinking material resin (g) surfactant (g) agent(g) basic substance (g) solvent pH A KW-3 (16) PC-6 (0.25) uril (1.35)diethanol amine (0.58) water/IPA (98.6:0.4) 8.96 B KW-3 (16) PC-6 (0.25)uril (1.35) diethanol amine (0.58) water/IPA (98.6:0.4) 9.71 C KW-3 (16)PC-6 (0.25) uril (1.16) N-methyl-2- water/IPA (98.6:0.4) 8.15pyrrolidone (0.27) D KW-3 (16) PC-6 (0.25) uril (1.16) tripropyl amine(0.68) water/IPA (98.6:0.4) 8.60 E KW-3 (16) TN-80 (0.25) uril (1.16) —water/TMAaq (90:3) 9.05 F KW-3 (16) TN-80 (0.25) uril (1.16) —water/TMAaq (70:30) 12.20 G KW-3 (16) TN-80 (0.25) uril (1.16)succinimido (0.70) water/IPA (98.6:0.4) 7.25 H KW-3 (16) PC-6 (0.25)uril (1.16) cyclohexane water/IPA (98.6:0.4) 7.80 carboxyamide (0.88) IKW-3 (16) PC-6 (0.25) uril (1.35) — water/IPA (98.6:0.4) 4.20 IPA:isopropyl alcohol TMAaq: aqueous solution of 2.38% by masstetramethylammonium hydroxide

Resist pattern thickening materials of A (example), E (example), F(example), G (example), and I (comparative example) were stored at about5° C. and at 25° C. independently for one month immediately after theirpreparation, and the pH values were measured. The results are shown inTable 2 together with those of immediately after their preparation.

TABLE 2 pH pH thickening immediately pH 25° C. material afterpreparation 5° C. for one month for one month A 8.96 8.99 8.99 E 9.059.05 9.04 F 12.20 12.23 12.20 G 7.25 7.20 7.20 I 4.20 3.95 3.73

The results of Table 2 show that pH values were approximately consistentbetween immediately after preparation, after one month at 5° C., andafter one month at 25° C. as for the resist pattern thickening materialsof A (example), E (example), F (example), and G (example), demonstratingtheir superior storage stability. On the contrary, the pH of the resistpattern thickening material of I (comparative example) changed into moreacidic during the storage at 5° C. for one month as well as at 25° C.for one month, demonstrating inferior storage stability. The reason isestimated that the resist pattern thickening material of I released oryielded a free acid during the storage and the free acid lowered the pH.

In addition, the thickening levels on a resist pattern were examinedwith respect to the resist pattern thickening materials of A (example),E (example), F (example), G (example), and I (comparative example) ofstored at about 5° C. for one month, stored at 25° C. for one month, andimmediately after their preparation.

Specifically, an element region was formed on a semiconductor substrateby a conventional process, then a layer of silicon oxide as aninterlayer insulating film was coated entirely on the element region bya CVD process. Then, a positive-type resist layer of alicyclic type ArFresist (positive-type resist AX5190, by Sumitomo Chemical Co.) wasformed on the silicon oxide layer, followed by irradiating ArF excimerlaser beam at an exposure of 50 mJ/cm² and developing, thereby to form ahole pattern in 250 nm thick.

Then, the resist pattern thickening materials of A (example), E(example), F (example), G (example), and I (comparative example) ofstored at about 5° C. for one month, stored at 25° C. for one month, andimmediately after their preparation were individually coated on the holepattern by a spin coating method, first under the condition of 1000rpm/5 sec, and then under the condition of 3500 rpm/40 sec to form eachlayer of the resist pattern thickening materials in about 100 nm thick.Thereafter, each layer of the resist pattern thickening materials wassubjected to baking of coated layer or baking for mixing at 100° C. for60 seconds, followed by rinsing by de-ionized water for 60 seconds todevelop the each layer and to remove the portions where interaction ormixing did not occur, consequently resist patterns thickened by theresist pattern thickening materials of A (example), E (example), F(example), G (example), and I (comparative example) were obtained. Table3 shows the space sizes as for the respective resist pattern thickeningmaterials.

TABLE 3 space size of resist swelled by space size of resist thickeningmaterial swelled by initial space size immediately after thickeningmaterial thickening of resist preparation after 25° C. for one material(nm) (nm) month (nm) A 110.2 81.6 80.5 E 110.2 91.3 92.3 F 110.2 88.687.1 G 110.2 90.2 91.0 I 110.2 68.0 60.3

The results of Table 3 show that space sizes were approximatelyconsistent when the resists were swelled by the resist patternthickening materials of A (example), E (example), F (example), and G(example) of immediately after preparation as well as after one month at25° C. that respectively exhibited pH stability as described above,demonstrating their superior stability with time, storage stability, andprocess uniformity. On the contrary, when the resists were swelled bythe resist pattern thickening material of I (comparative example), whichshowed acidic pH initially and the pH changed into more acidic duringthe storage at 5° C. for one month as well as at 25° C. for one month,the space sizes represented a change between immediately after thepreparation and after one month, demonstrating significantly inferiorproperties in stability with time, storage stability, and processuniformity.

-Formation of Thickening Resist Pattern (1)-

--Formation of Resist Pattern--

An element region was formed on a semiconductor substrate by aconventional process, then a silicon oxide layer as an interlayerinsulating film was formed over the entire element region by a CVD(chemical vapor deposition) process. Then, a positive-type resist layerof alicyclic type ArF resist (positive-type resist AX5190, by SumitomoChemical Co.) was formed on the silicon oxide layer, followed byirradiating ArF excimer laser beam at an exposure of 50 mJ/cm² anddeveloping, thereby to form a hole pattern in 250 nm thick. The spacesizes of the holes were shown in Table 4.

--Coating of Resist Pattern Thickening Material & Formation of ThickenedResist Pattern--

Then, the resist pattern thickening materials of A to I wereindividually coated on the hole pattern by a spin coating method, firstunder the condition of 1000 rpm/5 sec, and then under the condition of3500 rpm/40 sec to form each layer of the resist pattern thickeningmaterials in about 100 nm thick. Thereafter, each layer of the resistpattern thickening materials was subjected to baking of coated layer orbaking for mixing at 100° C. for 60 seconds, followed by rinsing byde-ionized water for 60 seconds to develop the each layer and to removethe portions where interaction or mixing did not occur, consequentlyresist patterns thickened by the resist pattern thickening materials ofA to I were obtained. Table 4 shows the space sizes due to therespective resist pattern thickening materials.

TABLE 4 initial space size space size of resist thickening of resistswelled by thickening material (nm) material (nm) A 110.2 81.6 B 110.282.0 C 110.2 80.3 D 110.2 79.0 E 110.2 91.3 F 110.2 88.6 G 110.2 90.2 H110.2 91.0 I 110.2 68.0

The results of Table 4 show that the resist pattern thickening materialsof A to H could thicken respectively the resist pattern and thethickening level of the resist pattern thickening material I(comparative example) was somewhat higher than those of A to H(examples).

-Formation of Thickening Resist Pattern (2)-

--Formation of Resist Pattern--

An element region was formed on a semiconductor substrate by aconventional process, then a silicon oxide layer as an interlayerinsulating film was formed over the entire element region by a CVDprocess. Then, a positive-type resist layer of alicyclic type ArF resist(positive-type resist AX5190, by Sumitomo Chemical Co.) was formed onthe silicon oxide layer, followed by irradiating ArF (argon fluoride)excimer laser beam at an exposure of 50 mJ/cm² and developing, therebyto form a trench or groove pattern in 250 nm thick. The widths of thetrench or groove were indicated in Table 5.

--Coating of Resist Pattern Thickening Material & Formation of ThickenedResist Pattern--

Then, the resist pattern thickening materials of A, B, C, D, and I wereindividually coated on the hole pattern by a spin coating method, firstunder the condition of 1000 rpm/5 sec, and then under the condition of3500 rpm/40 sec to form each layer of the resist pattern thickeningmaterials in about 100 nm thick. Thereafter, each layer of the resistpattern thickening materials was subjected to baking of coated layer orbaking for mixing at 100° C. for 60 seconds, followed by rinsing byde-ionized water for 60 seconds to develop the each layer and to removethe portions where interaction or mixing did not occur, consequentlyresist patterns thickened by the resist pattern thickening materials ofA to D, and I were obtained.

Table 5 shows the space sizes as for the respective resist patternthickening materials of A to D, and I.

TABLE 5 space size of resist initial space size swelled by thickening ofresist thickening material (nm) material (nm) A 201.0 161.0 B 201.0161.2 C 201.0 160.5 D 201.0 164.5 I 201.0 173.0

The results of Table 5 show that the resist pattern thickening materialsof A to D could thicken respectively the resist pattern and thethickening level of the resist pattern thickening material of I(comparative example) was somewhat higher than those of A to D(examples).

-Formation of Thickening Resist Pattern (3)-

--Formation of Resist Pattern--

An element region was formed on a semiconductor substrate by aconventional process, then a silicon oxide layer as an interlayerinsulating film was formed over the entire element region by a CVDprocess. Then, a positive-type resist layer of alicyclic type ArF resist(positive-type resist AX5190, by Sumitomo Chemical Co.) was formed onthe silicon oxide layer, followed by irradiating ArF excimer laser beamat an exposure of 50 mJ/cm² and developing, thereby to form plural typesof trench or groove patterns of which lengths and widths are shown inTable 6. The thickness of the resist layer was 250 nm.

--Coating of Resist Pattern Thickening Material & Formation of ThickenedResist Pattern--

Then, the resist pattern thickening materials of A, E, and I wereindividually coated on the plural types of trench or groove patterns bya spin coating method, first under the condition of 1000 rpm/5 sec, andthen under the condition of 3500 rpm/40 sec to form each layer of theresist pattern thickening materials in about 100 nm thick. Thereafter,each layer of the resist pattern thickening materials was subjected tobaking of coated layer or baking for mixing at 100° C. for 60 seconds,followed by rinsing by de-ionized water for 60 seconds to develop theeach layer and to remove the portions where interaction or mixing didnot occur, consequently resist patterns thickened by the resist patternthickening materials of A, E, and I were obtained.

Table 6 shows the space sizes of the plural trench patterns as for therespective resist pattern thickening materials of A, E, and I.

TABLE 6 space size of space size of space size of resist swelled resistswelled resist swelled initial space by thickening by thickening bythickening size of resist material A material E material I length (nm)/length (nm)/ length (nm)/ length (nm)/ width (nm) width (nm) width (nm)width (nm) 1205/101 18.5/17.0 30.5/28.0 60.4/18.0 1204/198 20.4/19.134.5/32.0 91.3/35.2 1198/305 23.1/21.0 33.0/31.0 116.5/58.0 

The results in Table 6 show that the resist pattern thickening materialsof A (example) and E (example) that exhibit alkaline representedsubstantially same space sizes in both directions of length and width,i.e. within 5 nm, even though the sizes of trench or groove of theresists were different, thus presenting substantially stable and uniformspace sizes without depending the sizes of pattern. On the contrary, theresist pattern thickening material of I (comparative example) the spacesizes were considerably longer in the length direction than the widthdirection, and the apace sizes changed depending on the size of trenchor groove of the resists.

EXAMPLE 2

As shown in FIG. 9, interlayer insulating film 12 was formed on siliconsubstrate 11. As shown in FIG. 10, titanium film 13 was formed by asputtering method on the interlayer insulating film 12. Then, as shownin FIG. 11, resist pattern 14 was formed. By using resist pattern 14 asa mask, the titanium film 13 was patterned by reactive ion etching suchthat openings 15 a were formed. Subsequently, as shown in FIG. 12,resist pattern 14 was removed by reactive ion etching, and openings 15 bwere formed in the interlayer insulating film 12 by using titanium film13 as a mask.

Then, titanium film 13 was removed by wet processing, and as shown inFIG. 13, TiN film 16 was formed on interlayer insulating film 12 by asputtering method. Subsequently, Cu film 17 was grown by an electrolyticplating method on TiN film 16. Then, as shown in FIG. 14, planarizingwas carried out by CMP such that the barrier metal and the Cu film orfirst metal film remained only in the groove portions corresponding tothe openings 15 b in FIG. 12, and wires 17 a of a first layer wereformed.

Then, as shown in FIG. 15, interlayer insulating film 18 was formed onwires 17 a of the first layer. Thereafter, in the same way as in FIGS. 9to 14, Cu plugs or second metal films 19 and TiN films 16 a, whichconnected the wires 17 a of the first layer to upper layer wires whichwould be formed later, were formed as shown in FIG. 16.

By repeating the above-described respective processes, as shown in FIG.17, a semiconductor device was fabricated which had a multilayer wiringstructure having, on the silicon substrate 11, the wires 17 a of thefirst layer, wires 20 of a second layer, and wires 21 of a third layer.Note that the barrier metal layers formed beneath the wires of therespective layers are not shown in FIG. 17.

In this Example 2, resist pattern 14 is a resist pattern fabricated inthe same way as in the case of Example 1, by using the resist patternthickening material of the present invention.

EXAMPLE 3

-Flash Memory and Process for Producing Thereof-

Example 3 is an example of the semiconductor device and process forproducing thereof according to the present invention using the resistpattern thickening material according to the present invention. Notethat, in Example 3, resist films 26, 27, 29, and 32 which will bedescribed hereinafter are resist films which have been thickened by thesame process as in Examples 1 and 2 by using the resist patternthickening material according to the present invention.

FIGS. 18 and 19 are top views or plan views of a FLASH EPROM (ErasableProgrammable Read Only Memory) which is called a FLOTOX (Floating GateTunnel Oxide) type or an ETOX (Electrically Tunneling Oxide) type. Notethat FIGS. 20 to 28 are cross-sectional schematic views for explainingan example of a process for producing the FLASH EPROM. In FIGS. 20 to28, the illustrations at the left sides are a memory cell portion (afirst element region), and are schematic diagrams of the cross-section(the A direction cross-section) of the gate widthwise direction (the Xdirection in FIGS. 18 and 19) of the portion at which a MOS (Metal OxideSilicon) transistor having a floating gate electrode is formed. Theillustrations at the center are the memory cell portion, which is thesame portion as in the left side drawings, and are schematic diagrams ofthe cross-section (the B direction cross-section) of the gate lengthwisedirection (the Y direction in FIGS. 18 and 19) which is orthogonal tothe X direction. The illustrations at the right side are schematicdiagrams of the cross-section (the A direction cross-section in FIGS. 18and 19) of the portion of the peripheral circuit portion or a secondelement region at which a MOS transistor is formed.

First, as shown in FIG. 20, field oxide film 23 of SiO₂ was selectivelyformed at the element isolation region on p-type Si substrate 22.Thereafter, first gate insulating film 24 a was formed at the MOStransistor of the memory cell portion (the first element region), by anSiO₂ film by thermal oxidation so as to become a thickness of 10 nm to30 nm. In a separate process, second gate insulating film 24 b wasformed at the MOS transistor of the peripheral circuit portion (thesecond element region), by an SiO₂ film by thermal oxidation so as tobecome a thickness of 10 nm to 50 nm. Note that, when the first gateinsulating film 24 a and the second gate insulating film 24 b are thesame thickness, these oxide films may be formed simultaneously in thesame process.

Next, in order to form a MOS transistor having depression typen-channels at the memory cell portion (the left side and the center inFIG. 20), the peripheral circuit portion (the right side in FIG. 20) wasmasked by resist film 26 for the purpose of controlling the thresholdvoltage. Then, phosphorus (P) or arsenic (As) was introduced, as ann-type impurity in a dosage amount of 1×10¹¹ cm⁻² to 1×10¹⁴ cm⁻² by anion implantation method, into the regions that were to become thechannel regions directly beneath the floating gate electrodes, such thata first threshold value control layer 25 a was formed. Note that thedosage amount and the conductive type of the impurity at this time canbe appropriately selected in accordance with whether depression typechannels or accumulation type channels are to be formed.

Then, in order to form a MOS transistor having depression typen-channels at the peripheral circuit portion (the right side in FIG.21), the memory cell portion (the left side and the center in FIG. 21)was masked by the resist film 27 for the purpose of controlling thethreshold voltage. Then, phosphorus (P) or arsenic (As) was introduced,as an n-type impurity in a dosage amount of 1×10¹¹ cm⁻² to 1×10¹⁴ cm⁻²by an ion implantation method, into the regions that were to become thechannel regions directly beneath the gate electrodes, such that a secondthreshold value control layer 25 b was formed.

Next, a first polysilicon film (a first conductor film) 28 having athickness of 50 nm to 200 nm was applied over the entire surface as afloating gate electrode of the MOS transistor at the memory cell portion(the left side and the center in FIG. 22) and as a gate electrode of theMOS transistor at the peripheral circuit portion (the right side in FIG.22).

Thereafter, as shown in FIG. 23, the first polysilicon film 28 waspatterned by using a resist film 29 formed as a mask, such that afloating gate electrode 28 a was formed at the MOS transistor at thememory cell portion (the left side and the center in FIG. 23). At thistime, as shown in FIG. 23, in the X direction, patterning was carriedout so as to obtain the final width, and in the Y direction, the regionwhich was to become the S/D region layer remained covered by the resistfilm 29 without patterning.

Next, as shown in the left side and the center of FIG. 24, after theresist film 29 was removed, a capacitor insulating film 30 a formed ofan SiO₂ film was formed by thermal oxidation to a thickness ofapproximately of 20 nm to 50 nm so as to cover the floating gateelectrode 28 a. At this time, a capacitor insulating film 30 b formed ofan SiO₂ film was formed on the first polysilicon film 28 of theperipheral circuit portion (the right side in FIG. 24). Here, althoughthe capacitor insulating films 30 a and 30 b were formed only by SiO₂films, they may be formed by a composite film of two to three layers ofSiO₂ and Si₃N₄ films.

Then, as shown in FIG. 24, second polysilicon film or second conductorfilm 31, which was to become a control gate electrode, was formed to athickness of 50 nm to 200 nm so as to cover the floating gate electrode28 a and the capacitor insulating film 30 a.

Then, as shown in FIG. 25, the memory portion (the left side and thecenter of FIG. 25) was masked by resist film 32, and the secondpolysilicon film 31 and the capacitor insulating film 30 b of theperipheral circuit portion (the right side in FIG. 25) were successivelyremoved by etching such that the first polysilicon film 28 was exposedat the surface.

Subsequently, as shown in FIG. 26, the second polysilicon film 31, thecapacitor insulating film 30 a and the first polysilicon film 28 a whichhad been patterned only in the X direction, of the memory portion (theleft side and the center of FIG. 26), were, by using the resist film 32as a mask, subjected to patterning in the Y direction so as to becomethe final dimension of a first gate portion 33 a. A laminate structureformed by control gate electrode 31 a/capacitor insulating film 30c/floating gate electrode 28 c, which had a width of approximately 1 μmin the Y direction, was formed. The first polysilicon film 28 of theperipheral circuit portion (the left side in FIG. 26) was, by using theresist film 32 as a mask, subjected to patterning so as to become thefinal dimension of second gate portion 33 b, and gate electrode 28 b ofa width of approximately 1 μm was formed.

Next, by using the laminate structure formed by the control gateelectrode 31 a/the capacitor insulating film 30 c/the floating gateelectrode 28 c of the memory cell portion (the left side and the centerof FIG. 27) as a mask, phosphorus (P) or arsenic (As) was introduced, ina dosage amount of 1×10¹⁴ cm⁻² to 1×10¹⁶ cm⁻² by an ion implantationmethod, into the Si substrate 22 of the element forming region, suchthat n-type S/D region layers 35 a and 35 b were formed. By using thegate electrode 28 b at the peripheral circuit portion (the right side ofFIG. 27) as a mask, phosphorus (P) or arsenic (As) was introduced, as ann-type impurity in a dosage amount of 1×10¹⁴ cm⁻² to 1×10¹⁶ cm⁻² by anion implantation method, into the Si substrate 22 of the element formingregion, such that S/D region layers 36 a and 36 b were formed.

Subsequently, the first gate portion 33 a of the memory cell portion(the left side and the center of FIG. 28) and the second gate portion 33b of the peripheral circuit portion (the right side of FIG. 28) werecovered by forming interlayer insulating film 37 formed of a PSG film toa thickness of about 500 nm.

Thereafter, contact holes 38 a, 38 b and contact holes 39 a, 39 b wereformed in the interlayer insulating film 37 formed on the S/D regionlayers 35 a, 35 b and the S/D region layers 36 a, 36 b. Thereafter, S/Delectrodes 40 a, 40 b and S/D electrodes 41 a, 41 b were formed. Inorder to form the contact holes 38 a, 38 b, 39 a and 39 b, the holepattern was formed with the resist material and then thickened theresist pattern with the resist pattern thickening material according tothe present invention, thereby forming fine space patterns (holepatterns). Thereafter, the contact holes were fabricated in accordancewith a conventional method.

In this way, as shown in FIG. 28, the FLASH EPROM was fabricated as asemiconductor device.

In this FLASH EPROM, the second gate insulating film 24 b of theperipheral circuit portion (the right side in FIGS. 20 to 28) is coveredby the first polysilicon film 28 or the gate electrode 28 b (refer tothe right side in FIGS. 20 to 28) always after formation. Thus, thesecond gate insulating film 24 b is maintained at the thickness at whichit was initially formed. Thus, it is easy to control the thickness ofthe second gate insulating film 24 b, and easy to adjust theconcentration of the conductive impurity in order to control thethreshold voltage.

Note that, in the above-described example, in order to form the firstgate portion 33 a, first, patterning is carried out at a predeterminedwidth in the gate widthwise direction (the X direction in FIGS. 18 and19), and thereafter, patterning is carried out in the gate lengthwisedirection (the Y direction in FIGS. 18 and 19) so as to attain the finalpredetermined width. However, conversely, patterning may be carried outat a predetermined width in the gate lengthwise direction (the Ydirection in FIGS. 18 and 19), and thereafter, patterning may be carriedout in the gate widthwise direction (the X direction in FIGS. 18 and 19)so as to attain the final predetermined width.

The example of fabricating a FLASH EPROM shown in FIGS. 29 to 31 is thesame as the above-described example, except that the processes after theprocess shown by FIG. 28 in the above example are changed to theprocesses shown in FIGS. 29 to 31. Namely, as shown in FIG. 29, thisexample differs from the above-described example only with respect tothe point that a polycide film is provided by forming a high meltingpoint metal film (a fourth conductor film) 42 formed of a tungsten (W)film or a titanium (Ti) film to a thickness of approximately 200 nm, onthe second polysilicon film 31 of the memory cell portion shown at theleft side and the center of FIG. 29 and on the first polysilicon film 28of the peripheral circuit portion shown at the right side in FIG. 29.The processes after FIG. 29, i.e., the processes shown in FIGS. 30 and31, are the same as those shown in FIGS. 26 to 28. Explanation of theprocesses which are the same as those shown in FIGS. 26 to 28 isomitted. In FIGS. 29 to 31, portions which are the same as those inFIGS. 26 to 28 are denoted by the same reference numerals.

In this way, as shown in FIG. 31, the FLASH EPROM was fabricated as asemiconductor device.

In this FLASH EPROM, high melting point metal films (the fourthconductor films) 42 a and 42 b were formed on the control gate electrode31 a and the gate electrode 28 b. Thus, the electrical resistance valuecould be decreased even more.

Note that, here, the high melting point metal films (the fourthconductor films) 42 a and 42 b were used as the high melting point metalfilm (the fourth conductor film). However, a high melting point metalsilicide film such as a titanium silicide (TiSi) film or the like may beused.

The example of fabricating a FLASH EPROM shown in FIGS. 32 to 34 is thesame as the above described example, except that a second gate portion33 c of the peripheral circuit portion (the second element region) (theright side in FIG. 32) also has the structure of the first polysiliconfilm 28 b (first conductor film)/an SiO₂ film 30 d (capacitor insulatingfilm)/a second polysilicon film 31 b (second conductor film) in the sameway as the first gate portion 33 a of the memory cell portion (the firstelement region) (the left side and center in FIG. 32), and that thefirst polysilicon film 28 b and the second polysilicon film 31 b areshort-circuited so as to form a gate electrode as shown in FIG. 33 orFIG. 34.

As shown in FIG. 33, opening 52 a, which passes through the firstpolysilicon film 28 b (first conductor film)/the SiO₂ film 30 d(capacitor insulating film)/the second polysilicon film 31 b (secondconductor film), is formed at a different place than, for example, asecond gate portion 33 c shown in FIG. 32, e.g., on insulating film 54.A third conductive film, for example, high melting point metal film 53 asuch as a W film or a Ti film or the like, is filled in the opening 52a. The first polysilicon film 28 b and the second polysilicon film 31 bare thereby short-circuited. Further, as shown in FIG. 34, opening 52 b,which passes through the first polysilicon film 28 b (first conductorfilm)/the SiO₂ film 30 d (capacitor insulating film), is formed. Thefirst polysilicon film 28 b, the lower layer, is exposed at the bottomportion of the opening 52 b. Thereafter, a third conductive film, forexample, high melting point metal film 53 b such as a W film or a Tifilm or the like, is filled in the opening 52 b. The first polysiliconfilm 28 b and the second polysilicon film 31 b are therebyshort-circuited.

In this FLASH EPROM, the second gate portion 33 c of the peripheralcircuit portion and the first gate portion 33 a of the memory cellportion have the same structure. Thus, the peripheral circuit portioncan be formed simultaneously with the formation of the memory cellportion. The fabricating process can thereby be simplified, which isefficient.

Note that the third conductor film 53 a or 53 b was formed separatelyfrom the high melting point metal film (the fourth conductor film) 42.However, they may be formed simultaneously as a common high meltingpoint metal film.

EXAMPLE 4

-Fabricating of Recording Head-

Example 4 relates to fabricating of a recording head as an appliedexample of the resist pattern of the present invention using the resistpattern thickening material according to the present invention. Notethat, in Example 4, resist patterns 102 and 126 which will be describedhereinafter are resist patterns which have been thickened by the sameprocess as in Example 1 by using the resist pattern thickening materialaccording to the present invention.

FIGS. 35 to 38 are process diagrams for explaining the fabricating ofthe recording head.

First, as shown in FIG. 35, a resist film was formed to a thickness of 6μm on an interlayer insulating film 100. Exposure and development werecarried out, so as to form the resist pattern 102 having an openingpattern for formation of a spiral, thin film magnetic coil.

Next, as shown in FIG. 36, plating substrate 106 was formed by vapordeposition on the interlayer insulating film 100, both on the resistpattern 102 and on the regions where the resist pattern 102 was notformed, i.e., the exposed surfaces of openings 104. The platingsubstrate 106 was a laminate of a Ti adhering film having a thickness of0.01 μm and a Cu adhering film having a thickness of 0.05 μm.

Next, as shown in FIG. 37, thin film conductor 108, which was formed bya Cu plating film of a thickness of 3 μm, was formed on the interlayerinsulating film 100, at the regions where the resist pattern 102 was notformed, i.e., on the surfaces of the plating substrate 106 formed on theexposed surfaces of the openings 104.

Then, as shown in FIG. 38, when the resist pattern 102 was melted andremoved and lifted off from the interlayer insulating film 100, thinfilm magnetic coil 110, which was formed by the spiral pattern of thethin film conductor 108, was formed.

The recording head was thereby fabricated.

At the obtained recording head, the spiral pattern was formed to be fineby the resist pattern 102 that was thickened by using the resist patternthickening material according to the present invention. Thus, the thinfilm magnetic coil 110 was fine and detailed, and was extremely wellsuited to mass production.

FIGS. 39 to 44 are process diagrams for explaining fabrication ofanother recording head.

As shown in FIG. 39, gap layer 114 was formed by a sputtering method tocover non-magnetic substrate 112 formed of ceramic. Note that aninsulator layer (not shown) formed of silicon oxide and a conductivesubstrate and the like (not shown) formed of an Ni—Fe permalloy wereformed in advance by a sputtering method to cover the non-magneticsubstrate 112, and a lower portion magnetic layer (not shown) formed ofan Ni—Fe permalloy was additionally formed on the non-magnetic substrate112. Then, resin insulating film 116, which was formed by athermosetting resin, was formed on predetermined regions on the gaplayer 114, except for the portions which were to become the magneticdistal end portions of the aforementioned lower portion magnetic layer(not shown). Next, a resist material was applied on the resin insulatingfilm 116 so as to form resist film 118.

Then, as shown in FIG. 40, the resist film 118 was exposed anddeveloped, such that a spiral pattern was formed. Subsequently, as shownin FIG. 41, the resist film 118 of the spiral pattern was subjected tothermosetting processing for about one hour at a temperature of severalhundred degrees Celsius, such that first spiral pattern 120, which wasshaped as projections, was formed. Then, conductive substrate 122 formedof Cu was formed to cover the surface of the first spiral pattern 120.

Next, as shown in FIG. 42, a resist material was coated on theconductive substrate 122 by a spin coating method so as to form a resistfilm 124. Thereafter, the resist film 124 was patterned on the firstspiral pattern 120, such that the resist pattern 126 was formed.

Then, as shown in FIG. 43, Cu conductor layer 128 was formed by aplating method on the exposed surface of the conductive substrate 122,i.e., at the regions where the resist pattern 126 was not formed.Thereafter, as shown in FIG. 44, by dissolving and removing the resistpattern 126, the resist pattern 126 was lifted-off from the conductivesubstrate 122, such that a spiral, thin film magnetic coil 130 formed ofthe Cu conductor layer 128 was formed.

In this way, a recording head, such as that shown in plan view in FIG.45, was fabricated which had magnetic layer 132 on the resin insulatingfilm 116 and had the thin film magnetic coil 130 on the surface.

At the obtained magnetic head, the spiral pattern was formed to be fineby the resist pattern 126 that was thickened by using the resist patternthickening material according to the present invention. Therefore, thethin film magnetic coil 130 was fine and detailed, and was extremelywell suited to mass production.

The present invention enables to solve the conventional problems andobtain following features.

Namely, the present invention provides a resist pattern thickeningmaterial which, during patterning a resist pattern to be thickened, canutilize laser or light as an irradiation source, and which can thicken aresist pattern formed of ArF resist or the like, and which has excellentmass productivity, and which can finely form a space pattern or wiringpattern, exceeding the exposure limits of irradiation sources. Thus theresist pattern thickening material according to the present invention issuitably applicable for a process for forming a resist pattern andprocess for producing a semiconductor device according to the presentinvention.

The process for forming a resist pattern according to the presentinvention is suitably applicable for functional parts such as a maskpattern, reticule pattern, magnetic head, LCD (liquid crystallinedisplay), PDP (plasma display panel), SAW filter (surface acoustic wavefilter) and the like, optical parts used for connecting to an opticalwiring, fine pats such as micro actuator and the like, and for producinga semiconductor. The process for forming a resist pattern thickeningmaterial according to the present invention is suitably utilized for aprocess for producing a semiconductor device according to the presentinvention.

The process for producing a semiconductor according to the presentinvention is suitably applicable for a producing procedure of varioussemiconductor devices, such as flash memory, DRAM, FRAM and the like.

In accordance with the present invention, various problems may be solvedthat have been demanded in the art.

Namely, in accordance with the present invention, a resist patternthickening material may be provided that exhibits superior storagestability and thickens a resist pattern uniformly, constantly andprecisely, without being effected substantially by environmental changessuch as temperatures and humidity, and storage period.

Further, in accordance with the present invention, a process for forminga resist pattern is provided that is capable to utilize excimer laserbeam, the thickening level of the resist pattern is controllableuniformly, constantly and precisely, without being effectedsubstantially by environmental changes such as temperatures andhumidity, and storage period, and space pattern of resist may be formedwith a fineness exceeding exposure limits or resolution limits ofavailable irradiation sources.

Further, in accordance with the present invention, a semiconductordevice having a fine wiring pattern is provided that is formed using afine space pattern of resist that is formed using the resist patternthickening material according to the present invention, and a processfor producing a semiconductor device adapted to effective massproduction of the semiconductor device.

1. A process for forming a resist pattern, comprising: forming a resistpattern, and coating a resist pattern thickening material on the resistpattern to thicken the resist pattern, wherein the resist patternthickening material comprises a resin, is capable of thickening theresist pattern by coating on the resist pattern, and exhibits a pH valueof above 7 and not over 14 at coating on the resist pattern or aftercoating on the resist pattern, wherein the content of the resin is 2.5%by mass to 3.2% by mass, wherein the resist pattern thickening materialfurther comprises a basic substance, wherein the basic substancecomprises a basic compound, and wherein the basic compound is at leastone selected from the group consisting of succinimide and cyclohexanecarboxyamide.
 2. The process for forming a resist pattern according toclaim 1, wherein the resist pattern exhibits a pH value of below 7 priorto thickening.
 3. The process for forming a resist pattern according toclaim 1, wherein the resist pattern is formed from at least one of anArF resist and a resist containing acrylic resin.
 4. The process forforming a resist pattern according to claim 1, wherein the resistpattern is subjected to baking under vacuum, prior to coating the resistpattern thickening material on the surface of the resist pattern.
 5. Aprocess for producing a semiconductor device, comprising: forming aresist pattern on a surface of workpiece, coating a resist patternthickening material on the resist pattern to thicken the resist patternto form a thickened resist pattern, and patterning the surface ofworkpiece by etching using the thickened resist pattern as a mask,wherein the resist pattern thickening material comprises a resin, iscapable of thickening the resist pattern by coating on the resistpattern, and exhibits a pH value of above 7 and not over 14 at coatingon the resist pattern or after coating on the resist pattern, whereinthe content of the resin is 2.5% by mass to 3.2% by mass, wherein theresist pattern thickening material further comprises a basic substance,wherein the basic substance comprises a basic compound, and wherein thebasic compound is at least one selected from the group consisting ofsuccinimide and cyclohexane carboxyamide.
 6. The process for producing asemiconductor device according to claim 5, wherein the surface ofworkpiece is a surface of a semiconductor substrate.
 7. A semiconductordevice, wherein the semiconductor device is produced by forming a resistpattern on a surface of workpiece, coating a resist pattern thickeningmaterial on the resist pattern, thickening the resist pattern to form athickened resist pattern, and patterning the surface of workpiece byetching using the thickened resist pattern as a mask, and wherein theresist pattern thickening material comprises a resin, is capable ofthickening the resist pattern by coating on the resist pattern, andexhibits a pH value of above 7 and not over 14 at coating on the resistpattern or after coating on the resist pattern, wherein the content ofthe resin is 2.5% by mass to 3.2% by mass, wherein the resist patternthickening material further comprises a basic substance, wherein thebasic substance comprises a basic compound, and wherein the basiccompound is at least one selected from the group consisting ofsuccinimide and cyclohexane carboxyamide.
 8. A process for forming aresist pattern, comprising: forming a silicon oxide layer over asemiconductor substrate on which an element region is formed, forming aresist pattern on the silicon oxide layer, and coating a resist patternthickening material on the resist pattern to thicken the resist pattern,wherein the resist pattern thickening material comprises a resin, iscapable of thickening the resist pattern by coating on the resistpattern, and exhibits a pH value of above 7 and not over 14 at coatingon the resist pattern or after coating on the resist pattern, whereinthe content of the resin is 2.5% by mass to 3.2% by mass, wherein theresist pattern thickening material further comprises a basic substance,wherein the basic substance comprises a basic compound, and wherein thebasic compound is at least one selected from the group consisting ofsuccinimide and cyclohexane carboxyamide.